The present invention relates to a printing apparatus for printing marks such as numerals, symbols, etc., on both upper and lower surfaces of a microminiature article such as a chip type part, for example, a rectangular chip capacitor, a rectangular chip resistor, or the like.
Although a chip type electronic part such as a chip capacitor, a chip resistor, or the like is very minute and is rectangular shaped having, for example, a width of 1.6 mm, a length of 3.2 mm, a thickness of 0.6 mm, and a weight of 10 mg, it must be printed to indicate a resistance value, an electrostatic capacity value, etc.
In the prior art, U.S. Pat. No. 3,122,994 or Japanese Patent Unexamined Publication No. 52653/84 teach printing apparatus for printing marks on the small article. The printing apparatus disclosed in U.S. Pat. No. 3,122,994 can print the marks on the small article such as a control relay or electronic timer which has a side more than several centimeters, but cannot print the marks on the microminiature article such as the chip type part.
Further, the printing apparatus disclosed in Japanese Patent Unexamined Publication No. 52653/84 can print the mark not only one surface (upper or lower surface) of the chip type part, but cannot print the marks on both surfaces. Therefore, a process to turn the printed surface to the upper side should be required when the electronic part is to be mounted on a printed substrate or the like.
In other words, an apparatus for printing a rated value, etc., on both upper and lower surfaces of the microminiature article has not been considered heretofore.